S-Adenosylmethionine (SAMe) is found in almost every tissue and fluid in the body. SAM plays a crucial role in the process called transmethylation. Methylation is involved in nearly every aspect of life. SAM is the primary “methyl” donor for a variety of methyl-transfer reactions in DNA, RNA, proteins, lipids, and small molecules in the body. Proper DNA methylation is essential for normal embryonic development. Methyl-transferase gene homozygously deleted (knocked out) has been proven lethal (Pegg, A. E., Feith, D. J., Fong, L. Y., Coleman, C. S., O'Brian, T. G., and Shantz, L. M., 2003, Biochem. Soc. Trans. 31, 356-360). DNA improperly methylated has been found in many tumors. Alterations in DNA methylation patterns induce the expression of oncogens or silence the expression of tumor suppressor genes, and methyl deficient diets have been shown to promote liver cancer in rodents.
The transsulfuration begins with S-adenosylhomocysteine (SAH), the residual structure of SAM upon donating the methyl group (transmethylation). Hydrolysis of SAH yields homocysteine, which in turns converts to cystathionine, then cysteine, and eventually, to glutathione, the hepatocellular antioxidant and life-saving detoxification agent.
The aminopropylation is another process initiated with SAM through decarboxylation. The decarboxylated SAM then couples with putrescine to generate spermidine and spermine which are critical to cell growth, differentiation and the stability of DNA and RNA. Furthermore, Methylthioadenosine (MTA), the by-product of polyamine synthesis, is a powerful analgesic and anti-inflammatory agent. This may be, at least partially, responsible for the clinical benefits observed in the treatment of osteoarthritis, rheumatoid arthritis and fibromyalgia with SAMe.
SAMe plays a role in the immune system, maintains cell membranes, and helps produce and break down brain chemicals, such as serotonin, melatonin, and dopamine. Deficiency of either vitamin B12 or foliate can reduce the level of SAMe. SAMe is also an antioxidant, a substance that protects the body from damaging reactive oxygen molecules in the body. These reactive oxygen molecules can come from inside the body or from environmental pollution and are thought to play a role in the aging process and the development of degenerative disease. In general, SAMe is thought to raise the level of functioning of other amino acids in the body.
By way of further background, S-adenosyl-1-methionine is a substrate of an enzyme lyase that converts S-adenosyl-1-methionine to the molecule methylthioadenosine and homoserine; it is an aminobutyric chain donor to tRNA; it is an aminoacidic chain donor in the biosynthesis of biotin; SAM-e, after decarboxylation, is the donor of aminopropyl groups for the biosynthesis of neuroregulatory polyamines spermidine and spermine. (Zappia et al (1979), Biomedical and Pharmacologcial roles of Adenosylmethionine and the Central Nervous System, page 1, Pergamon Press. N.Y.)
SAM-e has been used clinically in the treatment of liver disease (Friedel H, Goa, K. L., and Benfield P., (1989), S-Adenosyl-1-methionine: a review of its pharmacological properties and therapeutic potential in liver dysfunction and affective disorders in relation to its physiological role in cell metabolism. Drugs. 38, 389-416), arthritis (Di Padova C, (1987), S-adenosyl-1-methionine in the treatment of osteoarthritis: review of the clinical studies. Am J. Med. 83, (Suppl. 5), 6-65), and depression (Kagan, B, Sultzer D. L., Rosenlicht N and Gerner R. (1990), Oral S-adenosylmethionine in depression: a randomized, double blind, placebo-controlled trial. Am. J. Psychiatry 147, 591-595.) Alzheimer's patients have reduced cerebral spinal fluid levels of S-adenosyl-1-methionine (Bottiglieri et al, (1990), Cerebrospinal fluid S-adenosyl-1-methionine in depression and dementia: effects of treatment with parenteral and oral S-adenosyl-1-methionine. J. Neurol. Neurosurg. Psychiatry 53, 1096-1098.) In a preliminary study, SAM-e was able to produce cognitive improvement in patients with Alzheimer's disease. (Bottiglieri et al (1994), The clinical potential of admetionine (S-adenosyl-1-methioinine) in neurological disorders. Drugs 48, 137-152.) SAM-e brain levels in patients with Alzheimer's disease are also severely decreased. (Morrison et al, (1996), Brain S-adenosylmethionine levels are severely decreased in Alzheimer's disease, Journal of Neurochemistry, 67, 1328-1331.) Patients with Parkinson's disease have also been shown to have significantly decreased blood levels of SAM-e. (Cheng et al, (1997), Levels of L-methionine S-adenosyltransferase activity in erythrocytes and concentrations of S-adenosylmethionine and S-adenosylhomocysteine in whole blood of patients with Parkinson's disease. Experimental Neurology 145, 580-585.)
SAM-e levels in patients treated with the antineoplastic drug methotrexate are reduced. Neurotoxicity associated with this drug may be attenuated by co-administration of SAM-e. (Bottiglieri et al (1994), The Clinical Potential of Ademetionine (S-adenosylmethionine) in neurological disorders, Drugs, 48 (2), 137-152.)
Cerebral spinal fluid levels of SAM-e have been investigated in HIV AIDS dementia Complex/HIV encephalopathy and found to be significantly lower than in non-HIV infected patients. (Keating et al (1991), Evidence of brain methyltransferase inhibition and early brain involvement in HIV positive patients Lancet: 337:935-9.) Additionally, it is also known that Pneumocystis Carinii pneumonia (PCP) occurs when the host is immunosuppressed. The Pneumocystis pneumonia (PCP) in humans is associated with advanced HIV disease, severe malnourishment in children, and treatments for cancers, advanced cancers, rheumatic disease, and the prevention of organ transplant rejection (Perez-Leal et al. Am J Respir Cell Mol Biol Vol 45, PP1142-1146, 2011). It is fatal if untreated. Therefore early diagnosis is very important. Studies have been done regarding S-adenosylmethionine (SAM) levels in the diagnosis of Pneumocystis Carinii Pneumonia (PCP) in patients with HIV Infection. Because S-adenosylmethionine is required by Pneumocystis carinii in vitro, Pneumocystis infection depletes plasma SAM of rats and humans, nicotine reduces SAM of guinea pig lungs, and smoking correlates with reduced episodes of Pneumocystis pneumonia (PCP) in AIDS patients. Chronic nicotine treatment increases lung polyamine catabolic/anabolic cycling and/or excretion leading to increased SAM-consuming polyamine biosynthesis and depletion of lung SAM (J. Biological Chemistry 2005; 280(15):15219-15228). Therefore, severely decreased plasma SAM level predicts occurrence of PCP in patients with immunocompromised conditions only. The best treatment regimens for PCP should include keeping SAM level low as lowered SAM level helps to kill PCP pathogen, whereas, increasing SAM level is recommended for better outcomes of treating other diseases when SAM or MI is low.
De La Cruz et al have shown that SAM-e, chronically administered, can modify the oxidative status in the brain by enhancing anti-oxidative defenses. (De La Cruz et al, (2000), Effects of chronic administration of S-adenosyl-1-methionine on brain oxidative stress in rats. Naunyn-Schmiedeberg's Archives Pharmacol 361: 47-52.) This is similar to results obtained with SAM-e in liver and kidney tissue. Thus SAM-e would be useful as an antioxidant.
Oral SAM-e administration to patients with and without liver disease has resulted in increases in liver glutathione levels. (Vendemiale G et al, (1989), Effect of oral S-adenosyl-1-methionine on hepatic glutathione in patients with liver disease. Scand J Gastroenterol; 24: 407-15. Oral administration of SAM-e to patients suffering from intrahepatic cholestasis had improvements in both the pruritus as well as the biochemical markers of cholestasis. (Giudici et al, The use of admethionine (SAM-e) in the treatment of cholestatic liver disorders. Meta-analysis of clinical trials. In: Mato et al editors. Methionine Metabolism: Molecular Mechanism and Clinical Implications. Madrid: CSIC Press; 1992 pp 67-79.) Oral SAM-e administration to patients suffering from primary fibromyalgia resulted in significant improvement after a short term trial. (Tavoni et al, Evaluation of S-adenosylmethioine in Primary Fibromaylgia. The American Journal of Medicine, Vol 83 (suppl 5A), pp 107-110, 1987.) SAM-e has been used for the treatment of osteoarthritis as well. (Koenig B. A long-term (two years) clinical trial with S-adenosylmethionine for the treatment of osteoarthritis. The American Journal of Medicine, Vol 83 (suppl 5A), Nov. 20, 1987 pp 89-94)
SAM-e is clinically useful in many apparently unrelated areas because of its important function in basic metabolic processes. One of its most striking clinical uses is in the treatment of alcoholic liver cirrhosis that, until now, remained medically untreatable. Mato et al demonstrated the ability of oral SAM-e in alcoholic liver cirrhosis to decrease the overall mortality and/or progression to liver transplant by 29% vs 12% as compared with a placebo treated group. (Mato et al (1999), S-adenosylmethionine in alcohol liver cirrhosis: a randomized, placebo-controlled, double blind, multi-center clinical trial, Journal of Hepatology, 30, 1081-1089.)
In alcoholic liver, SAM is reduced whereas SAH and Hcy levels are increased. Two genes (MAT1A and MAT2A) encode for the essential enzyme methionine adenosyltransferase (MAT), which catalyzes the biosynthesis of S-adenosylmethionine (SAMe), the principal methyl donor and, in the liver, a precursor of glutathione. MAT1A is expressed mostly in the liver, whereas MAT2A is widely distributed. MAT2A is induced in the liver during periods of rapid growth and dedifferentiation. In human hepatocellular carcinoma (HCC) MAT1A is replaced by MAT2A. This is important pathogenetically because MAT2A expression is associated with lower SAMe levels and faster growth, whereas exogenous SAMe treatment inhibits growth (Lu, S C et al. Alcoho 35(3):227-34, 2005).
Sam-e also attenuates the damage caused by tumor necrosis factor alpha and can also decrease the amount of tumor necrosis factor alpha secreted by cells. Consequently, conditions in which this particular inflammatory factor is elevated would benefit from the administration of SAM-e. (Watson W H, Zhao Y, Chawla R K, (1999) Biochem J Aug. 15; 342 (Pt 1):21-5. S-adenosylmethionine attenuates the lipopolysaccharide-induced expression of the gene for tumour necrosis factor alpha.) SAM-e has also been studied for its ability to reduce the toxicity associated with administration of cyclosporine A, a powerful immunosuppressor. (Galan A, et al, Cyclosporine A toxicity and effect of the s-adenosylmethionine, Ars Pharmaceutica, 40:3; 151-163, 1999.)
SAM-e, incubated in vitro with human erythrocytes, penetrates the cell membrane and increases ATP within the cell thus restoring the cell shape. (Friedel et al, S-adenosyl-1-methionine: A review of its pharmacological properties and therapeutic potential in liver dysfunction and affective disorders in relation to its physiological role in cell metabolism, Drugs 38 (3):389-416, 1989)
SAM-e has been studied in patients suffering from migraines and found to be of benefit. (Friedel et al, S-adenosyl-1-methionine: A review of its pharmacological properties and therapeutic potential in liver dysfunction and affective disorders in relation to its physiological role in cell metabolism, Drugs 38 (3): 389-416, 1989)
SAM-e has been administered to patients with peripheral occlusive arterial disease and was shown to reduce blood viscosity, chiefly via its effect on erythrocyte deformability.
SAM-e is commercially available using fermentation technologies that result in SAM-e formulations varying between 60 and 80% purity. (That is, the final product contains 60-80% of the active or (S, S)-SAM-e and 20-40% of the inactive or (R, S)-SAM-e.) (Gross, A., Geresh, S., and Whitesides, Gm (1983) Appl. Biochem. Biotech. 8, 415.) Enzymatic synthetic methodologies have been reported to yield the inactive isomer in concentrations exceeding 60%. (Matos, J R, Rauschel F M, Wong, C H. S-Adenosylmethionine: Studies on Chemical and Enzymatic Synthesis. Biotechnology and Applied Biochemistry 9, 39-52 (1987). Enantiomeric separation technologies have been reported to resolve the pure active enantiomer of SAM-e. (Matos, J R, Rauschel F M, Wong, C H. S-Adenosylmethionine: Studies on Chemical and Enzymatic Synthesis. Biotechnology and Applied Biochemistry 9, 39-52 (1987; Hoffman, Chromatographic Analysis of the Chiral and Covalent Instability of S-adenosyl-1-methionine, Biochemistry 1986, 25 4444-4449: Segal D and Eichler D, The Specificity of Interaction between S-adenosyl-1-methionine and a nucleolar 2-0-methyltransferase, Archives of Biochemistry and Biophysics, Vol. 275, No. 2, December, pp. 334-343, 1989) Newer separation technologies exist to resolve enantiomers on a large commercial production scale at a very economic cost. In addition, it would be conceivable to synthesize the biologically active enantiomer using special sterioselective methodologies but this has not been accomplished to date.
De la Haba first showed that the sulfur is chiral and that only one of the two possible configurations was synthesized and used biologically. (De la Haba et al J. Am. Chem. Soc. 81, 3975-3980, 1959) Methylation of RNA and DNA is essential for normal cellular growth. This methylation is carried out using SAM-e as the sole or major methyl donor with the reaction being carried out by a methyltransferase enzyme. Segal and Eichler showed that the enzyme bound (S, S)-SAM-e 10 fold more tightly than the biologically inactive (R, S)-SAM-e thus demonstrating a novel binding stereospecificity at the sulfur chiral center. Other methyltransferases have been reported to bind (R, S)-SAM-e to the same extent as (S, S)-SAM-e and thus (R, S)-SAM-e could act as a competitive inhibitor of that enzyme. (Segal D and Eichler D, The Specificity of Interaction between S-adenosyl-1-methionine and a nucleolar 2-0-methyltransferase, Archives of Biochemistry and Biophysics, Vol. 275, No. 2, December pp. 334-343, 1989; Borchardt R T and Wu Y S, Potential inhibitors of S-adenosylmethionine-dependent methyltransferases. Role of the Asymmetric Sulfonium Pole in the Enzymatic binding of S-adenosyl-1-methionine, Journal of Medicinal Chemistry, 1976, Vol 19, No. 9, 1099-1103.)
SAM-e (whether in its optically pure enantiomeric form or in an enantiomeric or racemic mixture) presents certain difficult problems in terms of its stability at ambient temperature that result in degradation of the molecule to undesirable degradation products. SAM-e (and thus its enantiomers) must be further stabilized since it exhibits intramolecular instability that causes the destabilization and breakdown of the molecule at both high as well as ambient temperatures. SAM-e has therefore been the subject of many patents directed both towards obtaining new stable salts, and towards the provision of preparation processes that can be implemented on an industrial scale. The present patent thus envisions the use of any of the salts of SAM-e already disclosed in the prior art to stabilize the enantiomeric forms of SAM-e.
The clinical diagnostic field has seen a broad expansion in recent years, both as to the variety of materials of interest that may be readily and accurately determined, as well as the methods for the determination. Over the last several decades, testing for numerous substances such as drugs of abuse, or other biological molecules of interest has become commonplace. In recent years, immunoassay based on the interaction of an antibody with an antigen has been extensively investigated for this purpose. Based on the unique specificity and high affinity of antibodies, an immunoassay can accurately and precisely quantitate substances at the very low concentrations found in biological fluids.
In view of the importance of SAM, it is desirable to have an easy and reliable method to measure its concentration in a biological sample. A classical assay method for measurement of SAM in rat liver utilized the tripolyphosphatase activity that was associated with S-adenosylmethionine synthetase in rat liver. The tripoly-phosphatase activity is stimulated by low concentrations of S-adenosylmethionine. The assay sensitivity was reported at 0.1 nmole of SAM in an assay volume of 0.1 ml (i.e. 10-6 M). Samples were lyophilized, homogenized in acid, and centrifuged. The supernatant was then passed through Dowex 1 (HCO3-form) to remove endogenous inorganic phosphate and other potential interferons in the tissue. Great care has to be taken to avoid inorganic phosphate contamination from all reagents including the enzyme preparation, as well as glassware. The disadvantages of this assay are obviously lack of specificity, low sensitivity (1 μM),hard to control and compare between assays in different labs.
Another common method for measuring SAM in tissues or biological fluids is HPLC or electrophoresis after sample preparation normally encompassing the protein precipitation and/or extraction. Post column detection may include derivatization, then measurement through absorption, fluorescence, or electrochemical change, and more recently by Mass Spectrometry (MS), or Tandem Mass Spectrometry (MS/MS) or LC-MS/MS were obtained. Radioisotopes or stable isotopic molecules of SAM are frequently used for internal reference purpose. These methods are capable of measuring low level of SAM in serum or plasma; however, the process typically is laborious, time consuming and/or requires expensive equipment. Another drawback is that it usually does not distinguish the diastereoisomers of SAM at the sulfonium position. SAM is produced biologically in the (S,S) configuration at the sulfonium and a-aminoacid carbon respectively. Under normal physiological conditions or storage conditions, SAM spontaneously racemizes to form a mixture of (R,S) and (S,S) isomers. Most methyltransferases are reported to be specific to the (S,S) form of SAM only.
Another molecule of interest, S-Adenosylhomocysteine (SAH), is the precursor leading to the biosynthesis of SAM, as well as the product of all transmethylation reactions involving SAM as the methyl donor; i.e., SAH is metabolically linked to SAM, and structurally it contains a single carbon (as methyl) less than SAM. The co-existence and structure similarity of SAM and SAH present a great challenge to develop a method for the specific determination of the concentration of either molecule in a biological sample. The unstable (highly reactive) nature of SAM renders the level of difficulty for its determination even higher.
As the immediate precursor of all of the homocysteine (HCys) produced in the body, SAH has been suggested as a possibly more sensitive indicator for the risk of vascular disease than plasma HCys recently. The total plasma concentration of SAH is normally much lower than HCys. Like SAM, with no distinguished absorption, the determination of SAH in serum or plasma has been a challenge. Advanced method such as LC with post column derivatization, LC-MS/MS with internal reference is a recent development for its determination. However, these methods typically involve expensive instrumentations, laborious sample preparation, and time consuming procedures. Unlike SAM, however, SAH is a relatively stable compound; the sample handling and stability are usually not a problem.
Since SAH is the product of all methylation reactions involving SAM as methyl donor, increased concentration of SAH (or (SAH)) in tissues are frequently accompanied by decreased concentration of SAM ((SAM)). Therefore, the ratio of (SAM) and (SAH) may be a more sensitive indicator than the concentration of either SAM or SAH alone, particularly when their changes are subtle at early stages of dysfunction or abnormal conditions. The ratio of the concentration of SAM to the concentration of SAH known as “the methylation index” was first proposed by Cantani, et al. as an indicator of the methylating capacity of the cell. The ratio was later referred by M. S. Hershfield et al as methylation index (MI).
Therefore, a simple and convenient method that does not require costly instrumentation (LC, MS, and combinations) is clearly desirable for the determination of the biological concentration of SAM and to monitor change and metabolic paths in the body fluids, tissues and organelles. With the monoclonal antibodies against SAM and SAH becoming available as part of the instant invention, immunoassays will be available for research community and clinical labs to quantify SAM, SAH and MI conveniently, easily, accurately and quickly at low cost.
Similalrly and in view of the above, there is a need for improved methods for detection and diagnosis of cancer and other diseases, as well as methods for monitoring the progress of the diseases and monitoring the progress of various treatments for cancer and other diseases by quantitating the methylating index as a biomarker.